This invention relates to a method of, and apparatus for, wrapping articles in heat-sealable thin-gage film such as plastic.
While the method and apparatus of the present invention may be used for wrapping other articles, a typical article is a tray containing a meat product, as for example, lamb chops, chicken breasts, ground meat, steak, etc. After wrapping, the packages ultimately are placed for sale in the refrigerated display areas of stores, such as supermarkets. The articles referred to are typically wrapped in the cold rooms of supermarkets and central packaging plants, and the prior art has provided two basic types of apparatus for such wrapping. One type is a manual wrapping machine which is used to assist the operator in manual wrapping of the package. The second type is a fully automatic machine which receives the article, then proceeds to wrap and heat seal the package and to deliver the same, as to a conveyor belt. The present invention relates to the second type of machine, i.e., the fully automatic machine.
In one known prior-art automatic wrapping machine (Zimmerman U.S. Pat. No. 3,816,969) the article being wrapped is lifted from one level to another, and also reverses its direction of movement, during the wrapping sequence. In the machine of the present invention the article travels along a straight in-line horizontal path. In the Zimmerman patent, the article is pushed into a vertical wall of film. This is also done in the method and apparatus of the present application. However, in Zimmerman the trailing length of upper film is trucked under the package by raising the level and then reversing the direction of travel of the package. This is not done in the machine of the present application, and faster operation is possible.
In another prior-art patent (Holt, U.S. Pat. No. 3,659,398) the package follows a straight in-line path but the film is taken from a pre-cut or pre-sheeted supply and the upper film is formed by a forward overwrap movement. In the machine of the present application, the upper film is formed by rearward overwrap while the package is moving forwardly.